The present principles relate to a method and device for gamut mapping from a first color gamut towards a second color gamut. The method comprises obtaining a preserved key color (prsv_colorK0) and a hue alignment angle (⊖K0) of the key color (colorK0) for each key color (colorK0) of at least 3 key colors to define a preserved gamut and a rotated gamut; and performing a hue mapping of a current color (color) from the first color gamut towards the second color gamut wherein in case the current color (color) is in a preserved gamut defined by the preserved key color (prsv_colorK0), the hue mapped current color is unchanged, and in case the current color is out of the preserved gamut, the hue mapped current color is calculated from the hue alignment angle (⊖K0) of two adjacent key colors of the current color (rotated gamut) and from the preserved area.
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2. The method of claim 1, wherein projecting the key color is one of: an oblique projection, an orthogonal projection, a rotation around the origin in the chroma plane, a rotation around the preserved key color.
3. The method of claim 1, further comprising generating metadata relative to a preservation ratio used for invertible gamut mapping.
4. The method of claim 3, wherein a global preservation ratio is identified for any of three primary colors and three secondary colors in the wide color gamut.
5. The method of claim 3, wherein a preservation ratio is identified for each of the three primary colors and three secondary colors in the wide color gamut, thereby identifying a preserved area per sector.
6. The method of claim 1, further comprising generating metadata relative to a hue alignment angle used for invertible gamut mapping.
7. The method according to claim 6, wherein a hue alignment angle is defined for each of the three primary colors and three secondary colors in the wide color gamut.
8. The method of claim 1, wherein when the current color is in the preserved area defined by the preserved primary color, preserved adjacent secondary color and the origin of the chroma plane, the hue mapped current color is the current color.
10. The device according to claim 9, wherein projecting the key color is one of: an oblique projection, an orthogonal projection, a rotation around the center of the chroma plane, a rotation around the preserved key color.
11. The device according to claim 9, further comprising generating metadata relative to a preservation ratio used for invertible gamut mapping.
12. The device according to claim 11, wherein a global preservation ratio is identified for any of three primary colors and three secondary colors in the wide color gamut.
13. The device according to claim 11, wherein a preservation ratio is identified for each of the three primary colors and three secondary colors in the wide color gamut, thereby identifying a preserved area per sector.
14. The device according to claim 9, further comprising generating metadata relative to a hue alignment angle used for invertible gamut mapping.
15. The device according to claim 14, wherein a hue alignment angle is defined for each of the three primary colors and three secondary colors in the wide color gamut.
16. The device according to claim 9, wherein when the current color is in the preserved area defined by the preserved primary color, preserved adjacent secondary color and the origin of the chroma plane, the hue mapped current color is the current color.
18. The method according to claim 17, wherein the method comprises reconstructing a high dynamic range image from a standard dynamic range decoded image comprising the inverse gamut mapping from the standard color gamut towards the wide color gamut.
20. The device of claim 19, wherein the instructions are further operative to cause the device to perform reconstructing a high dynamic range image from a standard dynamic range decoded image comprising the inverse gamut mapping from the standard color gamut towards the wide color gamut.
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October 25, 2021
June 6, 2023
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